I don't get the thread...
It's comparing retail (which are practically ALWAYS cheaper than Digital prices) with the promotion. This part is only applicable if the games were cheaper on PSN prior to the "offer".
However, on top of that, it's actually a very common practice. The same happens whenever Disney do their Buy 1 Get 1 Free offer on DVD and Blu-ray. Films all go up to full RRP while the offer is on. Suddenly individual films are cheaper again once the offer ends.